Idiot’s Guide to Cutting and Fitting Planks

I had promised a separate post on planking. What shipwrights do is an ancient and mysterious art – there is a lot of well-written information in old musty books, and even some online – about spiling planks. This author will not be adding to that collection of information.

But there was a time when every small river along the northwest coast and the inlets of Puget Sound were dotted with fishermen and coastwise traders who would build their own boats and then work them. Some would build a boat and fish it for decades, others would build a boat, use it for a year or two, sell it, and then build a bigger one or one designed for a different fishery. These men were not shipwrights who built and repaired boats for other people – they simply gained the knowledge they needed to provide for themselves. What I am learning is more in the spirit of that. I have observed shipwrights in action over the years, and tried to learn what I can to be able to repair my own boat – if for no other reason than I can’t afford to pay somebody else $100.00 per hour to do it.

So the first step is to remove the old plank. In the picture below the old guard planks were removed (dark wood area) and the plank immediately below has been removed:


“Removing” planks from an 86 year old vessel is not as easy as it seems. She had been put together with iron square nails originally, and over the years silica bronze screws, stainless steel screws, and even galvanized lag bolts had been used. Here are some from the guard removal – and none of them wanted to come out easily:


Next, we cut some strips of 1/4″ plywood that are slightly undersize of the plank dimensions. These will be used for our patterns.


The plywood strips are tack-nailed into place where the missing plank is. If the plank is longer than the plywood, then two plywood strips are screwed together. Often they will have to be offset because the plank is not actually straight – that’s also why a 6 inch plank takes a 10 or 12 inch piece of wood to carve it out.

Once the plywood is tacked into place where the plank will be, I place white stickers just touching the planks above and below. I use one sticker for every frame, or rib, where the plank will be fastened. Then you carefully remove the pattern.


Set your plank stock out for measurement. Remember we went to Port Townsend to find this wood, which is Norwegian Larch that has been air-dried for over 20 years. Here you can also see that two pieces of plywood have been joined to form the proper length pattern. I place the pattern upside down so the white stickers are laying directly on the planking stock.


Once the pattern is tacked down, use a black magic marker to made a mark across the end of the sticker. This should now give you a sharp line exactly where the edge of the existing planks above and below are.


Once all the marks are made, you can remove the pattern. Then lightly set a nail in all the marks:


Then use a thin but sturdy strip of wood as a spiling batten, which you can use to trace the curve of the plank from nail to nail onto your planking stock:


Now we have a line for the saw to cut.



Always cut to the outside of the line, then use a planer to finish shaving down the plank edges for a tight fit. After it’s cut your straight piece of planking stock becomes a curved plank that fits just right (in theory).


The edges of the planks should fit tightly together, with the outer facing edges beveled in a V-shape to accept cotton and seam compound. It’s hard to see but in this picture the rear half of the planks are seated firmly together, the outward-facing half of the joint is beveled.


If you are going to remove more than one plank, as in the picture above, you mark the framed with the old plank edge before you remove the second plank. This mark can then be used when you make your pattern. The planks are then fastened (I use #14×3 stainless steel fasteners above the waterline and silica bronze below) and bent into place using clamps. It often takes some patience to keep shaving off bits here and there to get a tight fit. Then repeat and repeat until the bad wood is replaced by good wood:





While there are still planks that need to be replaced, half of the battle is making a realistic refit plan and prioritizing projects. Most of the bad planks are gone, but it was not realistic to tackle all of them this year. Also whenever a plank is removed, the frames behind it should be inspected and another frame added if warranted.


In the end we have a much safer and much stronger vessel. The real shipwrights, Reino and Ted, very kindly inspected my work and offered encouragement and advice. I feel like the boat and I are carrying on the maritime tradition of captains who take care of their own boats, learning just enough to be dangerous…




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